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Composite integral armor: processing, repair and mechanical characterization
2001 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The U.S. Army Composite Armored Vehicle (CAV) program introduced the concept of integrated composite armor (integral armor), which is a multi-functional hybrid lightweight structure consisting of different material layers aimed to provide unique ballistic and structural properties, multi-hit capability and FST protection (fire, smoke and toxicity). The CAV-program set baselines for future improvements in light-weight ballistic protection and cost-effective manufacturing for armor applications. One of the aspects to be improved is the repair of composite armor, which is the main object of study in the present work. The aim is to develop an induction-assisted repair procedure for level II damaged integral armor. The concept involves the use of conductive susceptor materials placed at the adhesive bondlines between the material layers. Induction heating is then used to accelerate the cure of the adhesive. Through the use of various susceptor combinations the temperature gradient created when using induction heating can be minimized, and a structure of uniform quality is obtained. The final procedure, in which carbon fiber fabric and steel meshes were used as susceptor materials, was able to minimize the through-thickness thermal gradient to only 5 °F. The total cure time was shortened to 50 minutes, which should be compared to a room temperature cure time of five to seven days. Generally, it can be concluded that the developed repair procedure is a good prototype for a future induction-assisted field or depot repair procedure. It provides guidelines in the areas of material choice (such as adhesives and susceptor materials), power settings and suitable cure cycles. And, last but not least, it has been shown that induction-assisted repair is well suited for level II damaged CIA. Additionally, a preliminary study on the effects of high strain rate damage on quasi-static mechanical properties of a carbon fiber reinforced polymer matrix composite is performed. Tensile, compression and shear specimens were subjected to dynamic loading in a split-Hopkinson pressure bar and were subsequently subjected to quasi-static mechanical testing. The mechanical properties were then compared to those of identical undamaged specimens. Generally, it can be said that the study is highly limited in many aspects, mainly due to the insufficient amount of data. It is concluded that several aspects of the performed tests need to be changed in order to obtain valid data that can lead to any conclusions on the effects of dynamic loading on the quasi-static mechanical properties of polymer matrix composites.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Composite Integral Armor, CIA, Vacuum Assisted Resin, Transfer Molding, VARTM, Repair, Induction, Split-Hopkinson, Pressure Bar, SHPB, Dynamic loading, Quasi-static loading
Keyword [sv]
URN: urn:nbn:se:ltu:diva-55107ISRN: LTU-EX--01/250--SELocal ID: c019d956-9b76-41d8-9bbf-912407c3f300OAI: diva2:1028488
Subject / course
Student thesis, at least 30 credits
Educational program
Materials Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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